This issue was addressed with a new entitlement. This issue is fixed in iOS 12.1. A local user may be able to read a persistent device identifier.
[
{
"product": "iOS",
"vendor": "Apple",
"versions": [
{
"lessThan": "12.1",
"status": "affected",
"version": "unspecified",
"versionType": "custom"
}
]
}
]